1. Technical Field
The present invention relates to a feeding device that includes a stacking portion on which a plurality of recording media are stacked, a feed roller that feeds the recording medium stacked on the stacking portion, and biasing means for applying biasing force to either the stacking portion or the feed roller to thereby decrease the distance between the stacking portion and the feed roller. The present invention also relates to a recording apparatus having the feeding device and a feeding method for use in the feeding device.
In the present invention, examples of the recording apparatus include an ink jet printer, a wire dot printer, a laser printer, a line printer, a copying machine, and a facsimile machine.
A liquid ejecting apparatus used herein is not limited to an ink jet recording apparatus, a copying machine, and a facsimile machine, which record data or images by ejecting ink onto a recording medium such as recording paper from a recording head as a liquid ejecting head. Other examples of the liquid ejecting apparatus include an apparatus that attaches liquid for a specific application, instead of ink, to an ejecting target medium corresponding to the recording medium by ejecting the liquid to the ejecting target medium from a liquid ejecting head corresponding to the recording head.
Examples of the liquid ejecting head include, in addition to the above-described recording head, a color-material ejecting head used in production of a color filter for a liquid crystal display or other apparatuses, an electrode-material (conductive paste) ejecting head used in formation of an electrode for an organic EL display, a field emission display (FED), or other apparatuses, a bioorganic-substance ejecting head used in production of a biochip, and a sample ejecting head as a precision pipette.
2. Related Art
In the past, for example, JP-A-2006-306616 discloses a feeding device installed in a recording apparatus includes a feed roller and a hopper configured to be movable toward and away from the feed roller. The hopper is biased toward the feed roller by a hopper lever. Specifically, one end of a torsion coil spring engages with the hopper lever, and the other end is fixed to a base portion of the feeding device. The torsion coil spring applies a biasing force to the hopper via the hopper lever.
FIG. 26 is a side sectional view illustrating an outline of the feeding device according to the related art.
As shown in FIG. 26, the feeding device 400 of the related art includes a base portion 411, a feed roller 401, a hopper 402, and a hopper lever 403. The hopper lever 403 is integrally formed with a cam follower 405 and is pivotable about a lever shaft 404. A first arm portion 407 of the torsion coil spring 406 engages with the hopper lever 403, and a second arm portion 408 engages with a spring fixing and engagement portion 413 of the base portion 411.
A hopper cam 409 configured to engage with the cam follower 405 is formed in a cam shaft 410. The hopper cam 409 is configured to be pivotable in the counter-clockwise direction in the drawing by the driving power of a feed motor (not shown). When the hopper cam 409 engages with the cam follower 405, the hopper lever 403 is pivoted in the clockwise direction in the drawing while resisting the biasing force of the torsion coil spring 406. At this time, the hopper 402 and the hopper lever 403 are integrally moved away from the feed roller 401. That is, a so-called hopper-down operation is carried out.
When the hopper cam 409 is pivoted further in the counter-clockwise direction, the hopper cam 409 is disengaged with the cam follower 405. Therefore, the hopper lever 403 is pivoted in the counter-clockwise direction by the biasing force of the torsion coil spring 406. At this time, the hopper lever 403 causes the hopper 402 to be moved toward the feed roller 401. That is, a so-called hopper-up operation is carried out. The sheet stacked on the hopper 402 is picked up by the feed roller 401 that rotates in the clockwise direction.
At the same time, feeding force is produced by the force that biases the sheet against the feed roller 401. Therefore, the sheet is fed out while being guided by a guide surface portion 412.
When the feeding operation is completed, the hopper cam 409 pivoted in the clockwise direction engages again with the cam follower 405, whereby the hopper-down operation is carried out.
However, the second arm portion 408 of the torsion coil spring 406 is fixed at the spring fixing and engagement portion 413 of the base portion 411. That is, the magnitude of the biasing force of the torsion coil spring 406 is not adjustable. However, a required sheet feeding force may vary in the course of the feeding operation. That is, there may be a case in which the sheet is fed by an excessive feeding force greater than a required force. In such a case, the energy is uselessly lost.
As another example, there may be a case in which the biasing force is unnecessarily large even when the sheet feeding operation is completed or before the feeding operation is started. In such a case, the energy loss is considerable.